De(n-methyl)-n-substituted derivatives of erythromycin

ABSTRACT

NEW DERIVATIVES OF ERTHROMYCIN A AND B, HAVING ANTIMICROBIAL ACTIVITY OF THE FORMULA   2-(ERY-O-),3-HO,4-(CH3-N(-Z)-),6-CH3-PERHYDROPYRAN   WHEREIN Z IS BENZYL; HALO, NITRO, AMINO, LOWERALKYL, LOWERALKOXY, CARBOXYBENZYL, HALOLOWERALKYL, DILOWERALKYLAMINOMETHYL, CARBOXY, LOWERALKOXYMETHYL, CYANO AND HYDROCARBYLENE SUBSTITUTED BENZYL; ALLYL, LOWERALKYL AND PHENYLSUBSTITUTED B AND Y ALLYL, E.G., CROTYL; CYANO; AND CYANOLOWERALKYL; AND ERY IS THE CLADINOSE AND ERYTHRONOLIDE MOIETIES OF ERYTHROMYCIN.

" d ates Patent omca 3,681,325 Patented Aug. 1, 1972 3 681,325 DE(N-METHYL)-N-SUBSTITUTED DERIVATIVES F ERYTHROMYCIN Leslie Alan Freiberg, Waukegan, Ill., asslgnor to Abbott Laboratories, North Chicago, Ill. No Drawing. Filed Sept. 30, 1970, Ser. No. 77,051 Int. Cl. C07c 47/18 U.S. Cl. 260-210 E 8 Claims ABSTRACT OF THE DISCLOSURE New derivatives of erythromycin A and B, having antimicrobial activity of the formula CH -lTI- Z 0 wherein Z is benzyl; halo, nitro, amino, loweralkyl, loweralkoxy, carboxybenzyl, haloloweralkyl, diloweralkylaminomethyl, carboxyl, loweralkoxymethyl, cyano and hydrocarbylene substituted benzyl; allyl, loweralkyl and phenylsubstituted ,3 and 'y allyl, e.g., crotyl; cyano; and cyanoloweralkyl; and cry is the cladinose and erythronolide moieties of erythromycin.

DISCLOSURE OF THE INVENTION This invention relates to derivatives of the antibiotic erythromycin which have antimicrobial activity. It especially relates to de(N-methyl)-N-substitutcd derivatives of erythromycin which have the general formula:

wherein W is one or more similar or dissimilar members selected from halogen, that is chloro, bromo and iodo, nitro, amino, cyano, loweralkyl' such for example as methyl, ethyl, iso-propyl etc., carboxybenzyl, loweralkoxy, such for example as methoxy, ethoxy, propoxy, haloloweralkyl, for example chloromethyl, chloropropyl, bromoethyl, diloweralkylaminomethyl such as methylethylaminomethyl, loweralkoxymethyl, carboxyl and when substituted on adjacent (vicinal) carbon atoms of the benzyl ring, two W groups can be combined to form a hydrocarbylene chain, e.g., a chain containing only hydrogen and carbon such as 1,3-butadienylene,

where R is hydrogen, phenyl and loweralkyl; and Where n is an integer having a value of 0-3 inclusive.

Clark and Freifelder in Antibiotics and Chemotherapy 8:483; September 1957, disclose de(N-methyl)-N-loweralkyl erythromycin and de-N-methyl-'y-phenylpropyl erythromycin together with a method for their preparation. The new compounds of this invention, while N- substituted derivatives of erythromycin, are found to have antibiotic activity not anticipated by the limited series theretofore disclosed.

It has now been found that by reacting de(N-methyl)- erythromycin A or B, depending on whether the A or B derivative of the product is desired, with a compound of the formula XY, the novel and useful erythromycin derivatives of this invention or their immediate precursors can be obtained. In the formula XY, X is halogen, either chloro, bromo or iodo, and Y is the equivalent of Z, except that the definition of Y excludes the instances Where W is amino and diloweralkylaminomethyl, which latter derivatives, as will be seen, are obtained from the reduction of the corresponding de(N-methyl)N-nitrosubstituted benzylerythromycin derivatives or by addition of diloweralkylamine to the de(N-methyl)-N-chloromethyl substituted benzyl erythromycins.

In carrying out the reaction between X-Y and de(N- methyl)erythromycin, the latter reactant in the A or B form can be obtained in accordance with the method set forth in U.S. Pat. 2,812,323. The reaction between XY and de(N-methyl)erythromycin A or B is suitably performed at temperatures ranging from 30 C. to +45 C. Preferably, however, the reaction is best carried out between 20 -C. and 30 C.

The duration of the reaction period required for the completion of the reaction ranges from 16 hours at 25 C. for the preparation of de(N-methyl)-N-benzylerythromycin A from benzyl chloride to 960 hours at 25 C. for the preparation of de(N-methyl)-N-o-nitrobenzylerythromycin A from o-nitrobenzyl chloride. Generally, the reaction is complete after 200 hours. It should be borne in mind that these time periods refer to substantially complete reactions and lesser reaction time will result in the formation of some product, although not the maximum that could be obtained by an extended reaction period.

The preparation of the de(N-methyD-N-substituted erythromycins by the reaction of de(N-methyl)erythromycin with XY is usually carried out in a solvent medium. Any inert solvent which is a solvent for one of the reactants and advantageously for both reactants can be utilized. The term inert is meant to include only those solvents that either undergo no irreversible reaction with the reactants or products, or react either at such a rate that byproduct formation is negligible or in such a way that by-product formation is controlled by the conditions of reaction.

Methanol is the preferred solvent although other solvents, such as the other lower alcohols, dimethylsulfoxide, and N,N-dimethylacetamide, can also be used to advantage.

While methanol is the preferred solvent, it can, especially at elevated temperatures, react with XY, forming YOCH and the acid HX. Acid formation should be controlled for two reasons. One reason is that acid can cause degradation of the erythronolide ring, the other reason being that it can protonate the de(N-methyl)-erythromycin as shall be discussed later.

So as to insure against such potentially harmful effects of acid, a bulfer can be employed. A preferred buffer is a base such as the salt of a strong base and a weak acid, sodium acetate being preferred. The addition of about 4 to about 7 equivalents of buffer for each equivalent of the basic de(N-methyl)erythromycin has been found sufficient.

As mentioned previously, acids can protonate the basic reactant de(N-methyl) erythromycin. The reaction initially produces de(N-methyl)-N-substituted erythromycin in the salt form. Therefore, a proton can transfer from this salt and protonate the stronger base, de(N-methyl)erythromycin. As the reaction progresses, more reactant can become protonated and halt the reaction prematurely prior to the utilization of all reactants. The inclusion of the buffer liberates any protonated species of reactant and promotes completion of the reaction.

Although the reaction between de(N-methyl)erythromycin and XY requires only an equimolar quantity of each reactant, it is desirable to employ an excess of one reactant, preferably an excess of XY. In the preferred method of preparation, XY is used in a ratio of 2-5 moles of XY of each mole of de(N-methyl)erythromy- Because the reaction appears to be a second order reaction, the rate of formation of product being a function of the concentration of the reactants, such an excess of X-Y would appear to enhance the reaction rate. The formation of product as a quaternary salt, however, is not a serious problem, even with a large excess of XY because of bulking efiect of the added substituent in the product together with its decreased nucleophilicity deters quaternary salt formation.

The novel de-N-methyl-N-substituted erythromycin derivatives of this invention are characterized by an antibacterial spectrum similar to that of erythromycin. These derivatives are useful as active ingredients of stable medicaments suitable for parenteral, topical and oral administration. In addition, they can be used in an aqueous solution as a disinfectant for various medical equipment where the surface of such equipment which is contaminated with Staphylococcus aureus is swabbed with a derivative of this invention at a concentration of at least in excess of its minimum inhibitory concentration, a concentration of 100-200 micrograms/ml. being satisfactory.

Reference to Table 1 will further illustrate the antibacterial characteristics of the compounds of this invention. Only the substituent Z is shown in the table, it being understood that Z is part of a compound as shown in the above formula.

The following specific examples are illustrative of the compounds of this invention together with the methods used to produce them.

EXAMPLE 1 De(N-methyl) -N-p-methylbenzylerythromycin A To a mixture of 4.00 g. (5.55 mole) of de(N-methyl)- erythromycin A and 3.02 g. (22.2 mole) of sodium acetate trihydrate dissolved in 40 ml. of absolute methanol is added 3.06 g. 16.5 mole) of a-bromo-p-xylene. The mixture was stirred at 25 for 24 hours and then poured into 200 ml. of water made basic with 10 ml. of concentrated ammonium hydroxide. The mixture was then extracted with four 50 ml. portions of chloroform. The combined chloroform layers were washed with 50 ml. of water containing 2.5 ml. of concentrated ammonium hydroxide, were dried over anhydrous sodium sulfate, and were then concentrated to give 7.43 g. of crude product mixture which was immediately purified 'by chromatograph as follows:

A column of g. of Florisil was prepared in benzene and made basic by eluting with 1.0 liter of benzene: 0.3% triethylamine. Fractions sizes were ml. and all eluents contained 0.3% triethylamine. The following fractions were collected.

Eluate (mg.) Eluent 2, 300 Benzene.

Fractions 2-13 were combined and dissolved in 15 ml. of absolute ethanol and 10 ml. of water was added to a slight turbidity. After standing until crystallization was complete the crystals were collected and dried, wt. .1.30 g., M.P. -161.

Analysis.-Calc. for C H NO (mol. wt., 824.074) (percent): C, 64.13; H, 8.93; N, 1.70; 0, 25.24. Found (percent): C, 64.07; H, 9.09; N, 1.60; 0, 25.07.

In an analogous manner, compounds represented by the following examples, 2 through 36, were prepared. The notation t refers to the duration of the reaction in hours; while the notation reactants denotes the composition of the reactant XY and whether the de-N-methyl erythromycin A or B was the starting material, i.e., A or B. Furthermore, the notation product only identifies the Z substituent of de-N-methyl-N substituted erythromycin A or -.B. The melting point of the product is shown under the heading MP. in degrees centigrade. Unless otherwise indicated, all reactions were carried out at 25 centigrade.

TABLE I.IN VITRO MINIMUM INHIBITORYggNCENTRATION Meg/m1. AGAR DILUTION p Staphylo- Streptococcus coccus K lebsiella Mycoplaama Mycoplasma Z aureus f qalli 11" p-Methylbenzyl 8. 1 1. 56 100 5 1. 0 1. 56 0. 39 12. 5 0. 25 5. 0 0. 39 0. 2 6. 2 0. 1 0. 5 3. 1 1. 56 100 2. 5 5. 0 0.39 0. 2 6. 2 0. 1 1. 0 0. 78 0. 78 25 1. 0 5. 0 0. 39 O. 78 100 2. 5 5.0 O. 78 0. 39 12. 5 1. 0 0. 25 0. 78 0. 2 6. 2 O. 25 0. 5 0. 89 O. 2 12. 5 0. 05 0. 25 0.39 0. 39 12. 5 0. 25 0. 5 0. 39 0. 1 12. 5 0. 5 0. 1 0. 78 0. 2 12. 5 0. 1 1. 0 0. 39 0. 39 12. 5 0. 25 0. 5 1. 56 0. 39 50 1. 0 5. 0 2,4,6-trimetl1ylb enzyl 6. 2 0. 39 100 1. 0 5. 0

t Reactants A or B Product M.P.

48 m-Chlorobenzyl chloride A m-Chlorobenzyl 127-131 16 m-Methylbenzylbromlde A m-MethylbenzyL- 116-121 48 p-Chlorobenzyl bromide A p-Chlorobenzyl..-

18 2,5-dimethylbenzyl chloride A 2,5-dimethylbenzyl.-.

18 2,4,6-trimethylbenzyl chlorlde A 2,4,6-tzimethylbenzyl 120 2-lso-propyl-5-nitro-benzyl chlorid A 2iso-propyl-5-nitrobe 70 yl bro de A All 16 Benzylbromlde A Be 48 p-Nitrobenzylbromlde A p-Nitrobenzyl...

18 o-Methylbenzyl bromlde A o-Methylbenzyl 72 Crotyl chloride A rotyl 120 B-Methylallyl chloride-. A B-Methylallyl.

120 p-Fluorobenzyl chloride A p-Fluorobenzyl.

72 m-Fluorobenzyl chloride. A m-Fluorobenzyl 119-125 72 p-Gdyanobenzyl chloride A p-CyanobenzyL..- 129-132 72 'y-I odbutyronitrlle A 'y-CyanopropyL 110-118 16 o-Methylbenzyl bromide B o-Methylbenzyl 105-109 70 m-Nitrobenzyl chloride A m-NitrobenzyL. 121-128 72 o-Fluorobenzyl chloride A o-Fluorobenz 120-123 16 m-Methylbenzyl bromide.-. m-Methy1benzyl 108-111 16 3,5-dlmethylbenzyl bromide. 3,5-din1ethylbenzyl... 135-147 72 p-tert-Butylbenzyl chloridep-tert-Butylbenzyl 139-142 72 l-ohloromethyl-naphthalene. a-(l-methylnaphthyl) 141-144 264 m-tert-Butylbenzyl chloride. m-tert-ButylbenzyL- 126-128 960 o-Nltrobenzyl chloride o-Nitrobenzyl 106-107 240 Propargyl chloride Propargyl 120-123 144 m-Methoxybenzyl chloride m-Methoxybenzyl 124-129 72 3,5-dl-tert-butylbenzyl bromide 3,5-dl-tert-buty1benzyL 130-137 240 2-methyl-5-nltro-benzy1chlorid (2-methyl5-nitro)benzy 128-130 18 3-chloropropenylbenzene--..; 3-(1-phenylpropenyl) 133-139 18 m-Methyloxymethylbenzyl bromide... A m-Methoxy methylbenzyl--. 114-116 768 Phenethyl-p-toluenesulionate A Phenethyl 113-116 18 tort-Butyl plus bromoacetate.. A tert-Butylglycyl 203-207 312 Benzyl-m-chloromethylbenzoat A m-(Carbobenzyloxy)benzyl 120 a,a-Dlchloro-pxylene A p-Chloromethylbenzyl EXAMPLE 37 methanol until the increase 1n weight reached g. The

m-Methoxymethylbenzyl bromide The reactant for 'Example 32 was made as follows. To a solution of 20.0 g. (75.7 mmole) a,a'-dibromo-mxylene was added a methanolic sodium methoxide solution prepared from 1.74 g. (75.7 mmole) of sodium and 100ml. of methanol. The mixture was warmed to re'flux while the pH was frequently checked. After minutes at reflux the pH was 7.0 and the mixture was cooled in an ice-bath, and then poured into 2.4 liters of water. The product was extracted with 1X 200 and 2X 100 ml. portions of chloroform. The combined chloroform layers were washed with 2X 100 ml. portions of water, were dried over sodium sulfate, and were evaporated. The residue (19.71 g.) was fractionally distilled through a 50 cm. Podbielniak column at 12.5 mm. Hg.

EXAMPLE 38 -De(N-methyl)4N-m-aminobenzyl erythromycin A A 2.03 g. (2.38 mmole) sample of de( N-methyl)-N-mnitrobenzylerythromycin A was dissolved in 250 ml. of ethanol. Raney nickel (2.0 g.) was added and the mixture was placed on a Parr shaker under a hydrogen atmosphere of 35 p.s.i. The theoretical uptake of hydrogen was observed in 1 hour. The catalyst was removed by filtration and the ethanol was evaporated to leave a glassy residue. The sample was purified by chromatography on 70 g. of Florisil using the procedure described in Example 1. Thin layer chromatography showed a single spot, but the sample could not be obtained in crystalline form. The infrared showed carbonyl absorptions at 1725 (lactone) and 1690 cm.- '(ketone).

Analysis.Calc. for C43H'12N2013 (825.060) (percent): C, 62.60; H, 8.80; N, 3.39; O, 25.21. Found (percent): C, 62.68; H, 8.95; N, 3.40; O, 25.41.

In a similar manner to m-aminobenzyl, the (Z-isopropyl-5-amino)benzy1; (2-methyl-5-amino)benzyl; p-aminobenzyl; and o-aminobenzyl-N-substituted derivatives of de-N-methyl erythromycin A or B can be prepared by reduction of the corresponding nitro derivatives.

EXAMPLE 39 De (N-methyl) -N-p-[ (dimethylamino) methyl] -benzy1 erythromycin A Dimethylamine was bubbled into 300 ml. of absolute product of Example 36 (8.59 g.) was dissolved in this mixture and allowed to stand at 25 for 3 hours. The mixture was then diluted with 1500 ml. of water and the product was extracted with 4x ml. portions of chloroform. The combined chloroform layers were washed with 250 ml. of water containing 15 ml. of concentrated ammonium hydroxide, were dried over sodium sulfate, and were evaporated to give 7.52 g. of crude product.

This material was purified in stages by column chromatography. Initially, the product was chromatographed on a column of 280 g. of Florisil prepared in benzene. Fractions of 250 ml. were collected and all eluents also contained 0.3% triethylamine.

The combined fractions of the first chromatography were individually examined by thin layer chromatography and those sufficiently enriched in the product were rechromatographed. For example, combined fractions 47- 51 contained predominantly the product along with three other nonpolar compounds. This material (0.85 g.) was chromatographed on a 70 g. column of Florisil prepared in benzene. Triethylamine (0.3%) was not added until the nonpolar compound had been eluted. Fractions were cut at ml. 1

Fraction 20 was pure and was dissolved in 4.5 ml. of ethanol and crystallized on standing after 6 ml. of water was added to give 0.21 g. of de(N-methyl)-N-p-[(dimethylamino)-methyl] benzyl erythromycin A, M.P. l26-128.

Analysis. Calc. for C46Hq3N2O13 (867.142) (percent): C, 63.72; H, 9.07; N, 3.23; O, 23.98. Found (percent): C, 63.66; H, 8.86; N, 3.13; O, 23.69.

In a similar manner combined fractions 52-57, 58-64, 65-70 and 71-76 were purified to give 1.2 g. of additional material.

Likewise, other diloweralkylamines including diethylamine, methyl ethylamine propylethylamine and the like can be reacted with de(N-methyl)N-methylbenzylerythromycin A or B. Such products include:

de-N-methyl-N-m-[ (diethylamino) -methyl]benzylerythromycin B de-N-methyl-N-p--[ (methylethylamino)-methyl] -benzylerythromycin B de-N-methyl-N-o-[ (methylpropylamino) -methyl] benzylerythromycin B de-N-methyl-N-p- (dipropylamino) -methyl] -benzylerythromycin A 7 EXAMPLE 4o De(N-methyl)-N-m-(dimethylamino)benzylerythromycin A A solution of 2.24 g. of de(N-methyD-N-m-aminobenzylerythromycin A was prepared in 150 ml. of ethanol and 4.5 ml. of formalin and 2.2 g. of 5% platinum on charcoal was added. The mixture was placed on a Parr shaker under a hydrogen atmosphere of 47 p.s.i. The theoretical uptake of hydrogen was observed in 24 hours. The catalyst was removed by filtration and the ethanol was evaporated to leave 2.70 g. of residue. The sample was purified by chomatography on 70 g. column of Florisil, prepared in benzene and made basic by eluting with 1.01 of benzene: 0.3% triethylamine. All eluents contained 0.1% triethylamine and fractions were cut at 125 ml. Elution of the column was conducted with benzene containing increasing percentages of ethyl acetate to a maximum of 20%. The appropriate fractions were combined and de(N methyl) N m (dimethylamino) benzylerythromycin A was crystallized from ethanol water.

The sample analyzed satisfactorily for a compound of the formula C H N O (mole wt. 853.115).

EXAMPLE 41 Benzyl m-chloromethylbenzoate To a mixture of 6.0 m1. of benzyl alcohol and 6.4 ml. of dry pyridine in 100 ml. of benzene was added a solution of 10.0 g. (52.8 mmole) of m-chloromethylbenzoyl chloride in 50 ml. of benzene during minutes. The mixture became warm for a period and was allowed to stand at 25 for 20 hours. The mixture was then washed with 100 ml. of water, followed by 4X 50 ml. of 1.2 N hydrochloric acid and finally with 50 ml. of water. The benzene was dried over sodium sulfate and evaporated to give 15.40 g. of crude product. The sample was distilled through a 50 cm. Podbielniak column to give 11.0 g. of benzyl m-chloromethylbenzoyl chloride, B.P. 187.5- 188.5" at 2.3 mm. Hg.

EXAMPLE 42 De(N-methyl)-N-m-(carbobenzyloxy)benzylerythromycin A To a mixture of 2.00 g. (2.78 mmole) of de(N- methy1)erythromycin A and 1.51 g. (11.1 mmole) of sodium acetate trihydrate dissolved in 20 ml. of absolute methanol was added 1.45 g. (5.55 mmole) of benzyl mchloromethylbenzoate. The mixture was sitted at 25 for 13 days and then poured into 250 ml. of water made basic with 5 ml. of concentrated ammonium hydroxide. The mixture was extracted with 4x 35 ml. portions of chloroform. The combined chloroform layers were washed with 100 ml. of water containing 5 ml. of concentrated ammonium hydroxide, were dried over anhydrous sodium sulfate, and were concentrated to give 4.27 g. of crude product mixture which was immediately purified by chromatography.

A column of 70 g. of Florisil was prepared in benzene and made basic by eluting with 1.0 liters of benzene: 0.3% triethylamine. Fraction sizes were 125 ml. and all eluents contained 0.3% triethylamine.

EXAMPLE 43 De(N-methyl)-N-m-carboxybenzyl-erythromycin A To a solution of 2.80 g. (2.96 mmole) of de(N- methyl)-N-m-(carbobenzyloxy)benzylerythromycin A in 50 ml. of ethanol was added 0.15 g. of 5% palladium on charcoal. The suspension was stirred at 25 under hydro gen at one atmosphere pressure. The theoretical amount of hydrogen was consumed in 5 hours. The catalyst was removed by filtration and the ethanol was evaporated. The residue was crystallized twice from chloroform to give 0.43 g. of de (N-methyl)-N-m-carboxybenzylerythromycin A, M.P. 151153.

I claim: 1. A compound of the formula cry-O CH wherein Z is:

and

-- 0H1)..CN

where W is one or more similar or dissimilarmernbers selected from the group consisting of halogen, cyano, loweralkyl, nitro, amino, carboxybenzyl, loweralkoxy, haloloweralkyl, carboxyl, diloweralkylaminomethyl, diloweralkylamino, loweralkoxymethyl, and when substituted on adjacent carbons of the benzyl ring, two W groups are 1,3-butadienylene; R is hydrogen, phenyl, and loweralkyl; ery is the cladinose and erythronolide moieties of erythromycin A and B; and n is an integer of from O3 inclusive.

2. A compound according to claim 1 in which Z is -(CH ),,CN. w

3. A compound according to claim 1 in which Z is CH2-CHECR.

4. A compound according to claim 1 in which Z is -CH --CR=C(R) 5. A compound according to claim 1 in 6. A compound according to claim 1 in which W is halogen, cyano, loweralkyl, nitro, carboxybenzyl, loweralkoxy, haloloweralkyl, carboxyl, loweralkoxymethyl, and when substituted on adjacent carbon atoms of the benzyl ring, two W groups are 1,3-butadienylene.

7. A compound according to claim 1 in which W is amino, diloweralkylamino and diloweralkylaminomethyl.

8. A compound according to claim 1 in which n is 0, and R is hydrogen.

which Z is References Cited UNITED STATES PATENTS 2,812,323 11/1957 Flynn et al 260210..E. 3,597,415 8/1971 Sinkula 260-210 LEWIS GOTTS, Primary Examiner I. R. BROWN, Assistant Examiner US. Cl. X.R. 260-999 UNITED STATES- PATENT OFFICE CE ATE OF CORRECTION Patent 3,681,325 Dated August 1, 1972 I Leslie Alan Freiberg It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as. shown below:

In Claim 3, please delete the forr nula CH2-CHECR and substitute therefor Signed and sealed this 21pm day of April 1973.

(SEAL) Attest:

' ROBERT GO'I'TSCHALK EDWARD M.FLETCHER,JR. Attesting Officer Commissioner of Patents 7 USCOMM-DC 60376-P69 u.s GOVERNMENT PRINTING OFFICE: I969 0-365-334 FORM PO-1050 (10-69) 

